diff --git a/lib/linguist/heuristics.rb b/lib/linguist/heuristics.rb
index 621d5635..39e286bb 100644
--- a/lib/linguist/heuristics.rb
+++ b/lib/linguist/heuristics.rb
@@ -283,7 +283,7 @@ module Linguist
     end
 
     disambiguate "Rust", "RenderScript" do |data|
-      if data.include?("^(use |fn |mod |pub |macro_rules|impl|#!?\[)")
+      if /^(use |fn |mod |pub |macro_rules|impl|#!?\[)/.match(data)
         Language["Rust"]
       elsif /#include|#pragma\s+(rs|version)|__attribute__/.match(data)
         Language["RenderScript"]